Electric water heater



Oct. 20, 1936.

IIII

H. BIDWELL ELEGTRI C WATER HEATER Filed Sept. 27, 1934 I II \26 y INVENTOR.

HOWARD BxDwELL Bgfw/M/ ATTORNEY.

Patented Oct. 20, 1936 UNITE STATES Parar orFicE 4 Claims.

This invention relates to apparatus for heating water, or other suitable fluid, by means of electric current passing therethrough.

It is one of the objects of the invention to provide means for the circulation of iiuid between the electrodes.

It is an object of the invention in one embodiment thereof to provide for maximum circulation of the uid between the electrodes in order to obtain maximum capacity for a given size of heater.

It is also an object of the invention in one embodiment thereof to provide .a heater of the electrolytic type which will automatically maintain l5 its energy consumption at a substantially constant value.

More specically stated it is an object of the invention, in the last-named embodiment thereof, to restrict and control the circulation of the fluid between the electrodes and limit the escape of steam generated therebetween so as to stabilize and render uniform the watt consumption of the device.

From the structural standpoint, it is a specific object of the invention to provide concentric vertically disposed tubes for simplicity and accuracy in construction in attaining the foregoing objects.

These and other objects of the invention will readily appear to those skilled in the art to which it appertains by a consideration of the following embodiments thereof taken in connection with the accompanying drawing in which Fig. 1 is a vertical section of one form of heater;

Fig. 2 is an elevation, partly in section, of the supporting bushing shown in Fig. l;

Fig. 3 is a vertical section of a modified form of heater; and

Fig. 4 is a plan view of the insulating disc shown in Fig. 3.

Referring to the drawing more in detail the reference character I I indicates a receptacle containing conductive fluid to be heated. This receptacle is provided with a reinforced portion or boss I2 through which extends a threaded aperture I3. The heating unit itself, which may be tubular in form, is mounted on a supporting bushing or base piece I4 which is threaded into the aperture I3. The base piece Ill has an axial aperture I5 therethrough for the reception of an insulating bushing I6. The bushing I6 has a leading-in rod Il extending through the center thereof which provides one terminal for the heating element, the other terminal of the circuit being provided by a ground connection, not

shown, to the receptacle itself. The base piece (Cl. 21S-40) I4 is provided with a circular recess I8 at the inner end thereof in which is pressed or otherwise secured a pipe or tubular member I9 which acts as one of the electrodes. The other electrode is a pipe or tubular member 29 of somewhat less diameter than the member I9 and is positioned coaxially with respect to the member I9. The opening at the lower end of the tubular member 29 is closed by a metallic disc 2| which may be pressed into place or otherwise securely fastened and the opening at the upper end of the member 29 is closed by another metallic disc 22 which may also be pressed into place. Each of the discs 2I and 22 is provided with a threaded aperture through the center thereof. The inner end of the leading-in rod II, which is threaded, is screwed into the lower disc 2 I. The upper end of the electrode I9 is closed by means of an insulating disc 23 which may be pressed into place and which is provided with an aperture 24 positioned centrally thereof. A machine screw 25 passes through the aperture 24 and is screwed into the threaded aperture in the disc 22 and thus the upper ends of the two electrodes I9 and 20 are held firmly in proper spaced relation. The outer electrode I9 is provided with one or more openings 2B near the lower end thereof and also one or more openings 21 at the upper end thereof. The inner electrode 29 may also be provided with an opening 28 in the wall thereof for a purpose presently to be described.

The insulating bushing I6 is provided with a collar 29 which may be integral therewith. The upper surface of this collar is preferably conical as indicated at 39 and the lower surface is preferably square or radial as` indicated at 3|. The cylindrical portion of the bushing which is toward the inner end from the collar 29, indicated at 32, may be of a somewhat smaller diameter than the cylindrical portion of the bushing, indicated at 33, which is toward the outer end of the bushing from the collar. The aperture I5 through the base piece IllV is, toward the inner end thereof, of a suitable diameter to fit the cylindrical portion 32 of the bushing I6 and is indicated by the reference character 34. The outer end of the aperture I5 is of a suitable diameter to t the outer portion 33 of the bushing and is threaded as indicated at 35. The form of the aperture between the inner portion 34 and the outer portion 35 is conical as indicated at 3G to correspond with the conical face 39 of the collar 29.

In assembling the insulating bushing in place a lock nut 31 is rst placed on the leading-in rod .Il so that the leading-in rod may be fastened rigidly to the disc 2|. A soft gasket 38 is interposed between the conical face 36 of the aperture and the collar 29 of the bushing and then a locking bushing 39 is used for holding all the parts in place. The locking bushing has an inner diameter to fit the outer portion 33 of the bushing and is threaded externally to correspond with the threaded aperture 35 of the base piece I4. As this locking bushing is screwed into place its inner end presses against the square surface 3| of. the collar 29 and presses the bushing tight against the gasket 38 thus providing a water tight joint. The threaded outer end of the leading-in rod l'l may be provided with two or more knurled nuts 40 for holding a conductor in place.

In operation the current fiows through the water, or other liquid contained in the receptacle, from the inner pipe or tubular member 20 to the outer tubular member I9 and in so doing heats the water through which it is flowing. The heated water then tends to rise, as indicated by the arrows A, and to fiow out through the openings 2`I into the receptacle II. There is thus set up a circulation whereby the heated water between the two electrodes is constantly being replaced by cooler water from the receptacle outside this annular space.

The opening 28 is provided in the wall of the inner member 20 so that any increase of pressure within this member may be relieved before it becomes so high as to cause serious damage. Without the provision of the opening 28 there might not be any water at all within the inner tube but if it should so happen that a little did leak through there might be steam formed and pressure generated of, a dangerous value before such pressure was released.

In the modified form shown in Figs. 3 and 4 the inner electrode 20 may be identical in construction with the inner electrode shown in Fig. 1. An upper insulating disc 23a which holds the two electrodes in proper spaced relation differs from the disc 23 of Fig. 1 in that the periphery thereof is provided with a plurality of notches 29a. An outer electrode I9a differs from the electrode I9 shown in Fig. 1 in two respects. The upper end of the electrode ISa extends beyond the insulating disc 23a and the opening therein is closed by a metallic disc 4I having a small aperture 42 centrally thereof. It is also provided with one or more openings 26 near the lower end thereof but does not have any opening near the upper end similar to the opening 21 shown in Fig. 1.

In the operation of. the modified form of the device shown in Fig. 3, the parts are so selected that the water in the annular space between the inner electrode 20 and the outer electrode Ilial is heated sufficiently to generate steam. The size of the small aperture 42 is such that the total steam generated, when the entire space between the electrodes is filled with water and available for conducting current, is unable to pass through the aperture 42 into the receptacle in which the heater is positioned. The steam will therefore gradually accumulate and occupy more and more space while the water will occupy less and less of the annular space at the bottom beneath the steam. This lowering of the water level in the annular space between the electrodes tends to reach an equilibrium for two reasons. First, as the water level becomes lower and lower, the cross section of the path through which the current iiows is less, the current becomes less, and the heating is less until the steam generated is no more than can fiow through the small aperture 42. Secondly, the hydrostatic pressure equal to the head of water, h, from the water level between the electrodes to the level of 'the aperture 42 forces more and more steam through the aperture as this head becomes greater. A simple and eifective apparatus is thus provided which automatically regulates itself. to a constant watt consumption which is a function of the amount of steam that will pass through the aperture 42.

It is one `of the characteristics of the type of heater shown herein that the conductivity of the electrolyte varies greatly with its temperature with the result that such a heater has a tendency to draw very little current when it is first started up and is cold and after it has had an opportunity of getting warm the current becomes altogether too high. There are therefore numerous applications for such a heater where itis absolutely necessary, to render it satisfactory commercially, that some sort of controlling means be provided and the simplicity and inexpensiveness of the means disclosed in Fig. 3 make such a type of control very valuable.

While the electrodes are shown in Fig. 3 as concentrically disposed cylindrical members the method herein described of controlling the value of the watt consumption of the heater is not necessarily conned to this type of construction. Any closed chamber which is partly filled with liquid and partly lled with a gas generated by heating the liquid and in which the electrodes are vertically disposed so as to be partly submerged and partly above the liquid and in which the escape of the vaporized fluid is limited and controlled by an orice is adapted for carrying out the purpose of automatically controlling the wattage consumption.

It is to be understood that the above described embodiments of the invention are for purposes of illustration only and various changes may be made therein without departing from the spirit and scope of the invention as defined in the subjoined claims.

I claim:

1. An immersion heater of the type in which the fluid being heated furnishes a conductive path for the current, a metallic base having an outer thread adapted to be screwed into the bottom wall of a receptacle containing a fluid to be heated, a vertically disposed tube extending upwardly from said base, an insulating disc at the upper end of said tube forming therewith and said base a closed chamber, a second smaller tube positioned coaxially within said rst-named tube, a metallic disc in each end of said smaller tube and secured thereto, an insulating bushing positioned centrally of said base, a leading-in member positioned within said bushing, means for securing the upper metallic disc of the small tube to the insulating disc of the larger tube and means for securing the lower metallic disc to the leadingin member.

2. In a device of the character described, a. vertically disposed tube, a closure for the upper end thereof having an orifice of restricted crosssectional area therein, a second tube positioned concentrically within said first-named tube, a closure for the upper end of said second-named tube, insulating spacing means between the upper end of the smaller tube and the outer tube having a plurality of passages therein, a metallic closure for the lower end of said smaller tube, and an insulating bushing carrying leading-in means for supporting said metallic closure and tube and for supplying current thereto.

3. An immersion heater of the type in which the uid being heated furnishes a conductive path for the current, a metallic base having an outer thread adapted to be screwed into the Wall of a receptacle containing a fluid to be heated, an insulating bushing positioned centrally of said base, a leading-in member positioned Within said bushing, a tubular member secured to said leadingin member to serve as an electrode of one polarity, and a second tubular member having an inner diameter greater than the outer diameter of said rst-named tubular member and an outer diameter less than the diameter of said outer thread secured to said base to serve as an electrode of the other polarity.

4. In a device of the character described, a vertically disposed tube, a closure for the upper end thereof having an orifice of restricted cross-sectional area therein, a second tube positioned concentrically Within said first-named tube, insulating spacing means between the upper end of the smaller tube and the outer tube having a plurality of passages therein, and an insulating bushing carrying leading-in means for supporting said second-named tube and for supplying current thereto.

HOWARD BIDWELL. 

